Caspase-3在成年大鼠中枢神经系统分布的免疫组织化学研究

采用免疫组织化学ABC法观察caspase3在成年大鼠中枢神经系统不同区域内的分布。caspase3阳性反应产物主要分布于脊髓前角和侧角大型运动神经元及中型神经元的胞浆、胞核及突起;脊髓后角及灰质连合的中、小型神经元的胞核及胞浆亦可见caspase3阳性反应产物;脊髓白质内的星形胶质细胞、小胶质细胞及少突胶质细胞的胞核和胞浆,caspase3阳性反应产物呈强阳性反应。在延髓内,caspase3阳性反应产物定位于中央灰质、三叉神经尾侧亚核和中央网状核内中型神经元的胞浆。大脑皮层各区内的caspase3阳性反应产物集中分布于ⅢⅤ层锥体细胞的胞浆,呈弱阳性反应。海马的CA1、CA2、CA3、CA4区的锥体细胞层的细胞,胞浆亦呈弱阳性反应。小脑内,以Purkinje细胞胞浆着色为主。乳头体核、尾状核、豆状核、嗅前核后部、嗅结节及丘脑等部位亦可见caspase3阳性神经元。本研究的结果说明caspase3在中枢神经系统内广泛分布,且在不同部位神经元的亚细胞分布存在差异。     

Dynamics of the junction between the medulla and the cervical spinal cord: An in vivo study in the sagittal plane by magnetic resonance imaging

Summary Sagittal sections of the brain-stem made by MRI reveal differences in the angle formed by the medulla and the cord. In order to study the normal mobility of this region of the CNS during flexion and extension of the head, sagittal MRI studies were made in the sagittal plane in 18 young volunteers. The volunteers were in dorsal decubitus with the cervical spine first flexed and then extended, with the movement localized to the cranio-cervical junction as far as possible. T1-weighted sequences were used, with body coils in 16 cases and surface coils in two. Measurements were related to global cranio-cervical range of movement, movement at the craniocervical junction and spino-medullary movement. Variations in the depth of the free space in front of the medulla, pons and spinal cord during movement were also noted. We also checked for downward shift of the lower part of the 4th ventricle and modification of the shape of the ventricle during flexion-extension. The global range of cranio-cervical movement was between 31 and 100° (average 63°). The range between the cranium and C1C2 was 4 to 39° (average 19°) and the spino-medullary range was from 1 to 32° (average 14°). During flexion, the free space narrowed in front of the pons 11 times, in front of the medulla 14 times and in front of the cervical cord 11 times. There was a downward shift of the lower part of the 4th ventricle during flexion in 4 cases but no change in shape was noted. Though this study is open to criticism from several aspects, it may be concluded that variations of the spino-medullary angle in the sagittal plane during flexion-extension do occur, that they are closely correlated with movements at the cranio-cervical junction, and that the spino-medullary junction moves forward during flexion.

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Dynamique de la jonction bulbomédullaire et de la moelle cervicale: Étude in vivo dans le plan sagittal en imagerie par résonance magnétique

Résumé Dans le but d'étudier la mobilité normale de la jonction bulbomédullaire durant la flexionextension de la tête, nous avons exploré en IRM dans le plan sagittal 18 jeunes volontaires. L'appareil Magniscan 0,15 Tesla a été utilisé avec des séquences de spin écho courtes, 16 fois en antenne corps et 2 fois en antenne de surface. Dans les limites de notre méthodologie, le secteur global de mobilité cervico-céphalique varie de 31 à 100° (moyenne 63°), le secteur de mobilité O-C1C2 varie de 4 à 39° (moyenne 19°), le secteur de mobilité bulbomédullaire varie de 1 à 32° (moyenne 14°). Lors de la flexion, l'espace libre diminue 11 fois devant la protubérance, 14 fois devant le bulbe et 11 fois devant la moelle cervicale. La partie basse du V4 s'abaisse dans 4 cas en flexion. Aucune modification de la forme du V4 n'a pu être notée. Bien que cette étude soit critiquable à bien des égards, nous pouvons affirmer: que les variations de l'angle bulbomédullaire dans le plan sagittal durant la flexion-extension de la tête sont effectives; qu'elles sont étroitement corrélées à celles de la charnière cranio-rachidienne; que durant le mouvement de flexion, la jonction bulbomédullaire se déplace en avant.

     

Peripheral nerve grafts lacking viable Schwann cells fail to support central nervous system axonal regeneration

Summary Peripheral nerve grafts were implanted bilaterally into the diencephalon of adult hamsters. One graft segment contained both viable Schwann cells and their basal lamina tubes. The Schwann cell population in the second graft segment was killed by freezing prior to implantation. Seven weeks after graft implantations, the extracranial end of each graft segment was exposed, transected and labelled with a fluorescent tracer substance. One week after the labelling procedure each animal was perfused and the diencephalon and midbrain were examined. Ultrastructural analyses of both types of graft demonstrated the persistence of the Schwann cell-derived basal lamina tubes. Retrogradely labelled neurons were found in all cases in which an intact graft remained in place for two months, but were seen in only one case with a frozen graft. Large numbers of myelinated and unmyelinated axons were seen within the intact grafts, but no axons were found in the previously frozen grafts. These results indicate that lesioned CNS axons are able to regenerate vigorously when provided with an environment which includes viable Schwann cells. But, CNS axons regenerate less well, if at all, when Schwann cells are absent. Further, it appears that Schwann cell-derived basal lamina tubes, when isolated from their parent cells, are insufficient to initiate or sustain CNS axonal regeneration.This material is based upon work supported by the National Science Foundation under grant BNS-8416911     

T cell epitope spreading to myelin oligodendrocyte glycoprotein in HLA-DR4 transgenic mice during experimental autoimmune encephalomyelitis

Epitope spreading has been implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and human multiple sclerosis (MS). T cell epitope spreading has been demonstrated in rodents for myelin basic protein (MBP) and proteolipid protein (PLP) determinants, but not for myelin oligodendrocyte glycoprotein (MOG), another important myelin antigen. Moreover, the role of human autoimmunity-associated MHC molecules in epitope spreading, including HLA-DR2 and DR4, has not been formally examined. To address these questions, we investigated epitope spreading to MOG determinants in HLA-DR4 (DRB1*0401) transgenic mice during EAE. The data show that upon induction of EAE in HLA-DR4 transgenic mice with the immunodominant HLA-DR4-restricted MOG peptide 97-108 (MOG(97-108); TCFFRDHSYQEE), the T cell response diversifies over time to MOG(181-200) (core: MOG(183-191); FVIVPVLGP) and MBP. The spreading epitope MOG(181-200) binds with high affinity to HLA-DRB1*0401 and is presented by human HLA-DRB1*0401+antigen presenting cells. Moreover, this epitope is encephalitogenic in HLA-DRB1*0401 transgenic mice. This study demonstrates intra- and intermolecular epitope spreading to MOG and MBP in "humanized" HLA-DR4 transgenic mice.     

Central effects of aldosterone infused into the rat subcommissural organ region

D-Aldosterone (5 ng/microliter/h) was infused for 6 days into the region of the subcommissural organ (SCO) of conscious, adult male Sprague-Dawley rats. Aldosterone increased urinary sodium loss and the sodium/potassium ratio. Although probably central in origin, these effects still occurred when cannulae were displaced up to 1 mm from the targeted SCO placement. Aldosterone decreased adrenal medullary cross-sectional area without affecting cell density. This effect was highly dependent on proper cannula placement and was not observed when the cannula tip was not in contact with the cerebrospinal fluid of the pineal recess over the rostral two-thirds of the SCO. We conclude that aldosterone increases sodium excretion by an action in the SCO and/or adjacent structures. We also postulate a negative trophic relationship between mineralocorticoids and the adrenal medulla mediated by the SCO.     

Amino acid substitutions within the heptad repeat domain 1 of murine coronavirus spike protein restrict viral antigen spread in the central nervous system

Targeted recombination was carried out to select mouse hepatitis viruses (MHVs) in a defined genetic background, containing an MHV-JHM spike gene encoding either three heptad repeat 1 (HR1) substitutions (Q1067H, Q1094H, and L1114R) or L1114R alone. The recombinant virus, which expresses spike with the three substitutions, was nonfusogenic at neutral pH. Its replication was significantly inhibited by lysosomotropic agents, and it was highly neuroattenuated in vivo. In contrast, the recombinant expressing spike with L1114R alone mediated cell-to-cell fusion at neutral pH and replicated efficiently despite the presence of lysosomotropic agents; however, it still caused only subclinical morbidity and no mortality in animals. Thus, both recombinant viruses were highly attenuated and expressed viral antigen which was restricted to the olfactory bulbs and was markedly absent from other regions of the brains at 5 days postinfection. These data demonstrate that amino acid substitutions, in particular L1114R, within HR1 of the JHM spike reduced the ability of MHV to spread in the central nervous system. Furthermore, the requirements for low pH for fusion and viral entry are not prerequisites for the highly attenuated phenotype.     

Hippocampal neuron and synaptophysin-positive bouton number in aging C57BL/6 mice

A loss of hippocampal neurons and synapses had been considered a hallmark of normal aging and, furthermore, to be a substrate of age-related learning and memory deficits. Recent stereological studies in humans have shown that only a relatively minor neuron loss occurs with aging and that this loss is restricted to specific brain regions, including hippocampal subregions. Here, we investigate these age-related changes in C57BL/6J mice, one of the most commonly used laboratory mouse strains. Twenty-five mice (groups at 2, 14, and 28–31 months of age) were assessed for Morris water-maze performance, and modern stereological techniques were used to estimate total neuron and synaptophysin-positive bouton number in hippocampal subregions at the light microscopic level. Results revealed that performance in the water maze was largely maintained with aging. No age-related decline was observed in number of dentate gyrus granule cells or CA1 pyramidal cells. In addition, no age-related change in number of synaptophysin-positive boutons was observed in the molecular layer of the dentate gyrus or CA1 region of hippocampus. We observed a significant correlation between dentate gyrus synaptophysin-positive bouton number and water-maze performance. These results demonstrate that C57BL/6J mice do not exhibit major age-related deficits in spatial learning or hippocampal structure, providing a baseline for further study of mouse brain aging.     

顺铂和替加氟联合放疗治疗中晚期食管癌疗效观察

目的观察顺铂和替加氟联合放疗治疗食管癌的临床疗效及其毒副反应。方法2003年1月至2006年2月对60例食管癌患者采取顺铂20mg·m-2·d,替加氟750mg·m-2·d,连用5天,序贯放疗60~70Gy/6~7周。结果60例患者中,CR24例,PR18例,SD9例,PD9例,RR(CR+PR)为70·0%,主要毒副作用为骨髓抑制、恶心呕吐。肝肾功损害及口腔炎、静脉炎等较轻。结论顺铂和替加氟联合放疗治疗食管癌疗效好,耐受性好值得推广应用。     

Regionally defective colonization of the terminal bowel by the precursors of enteric neurons in lethal spotted mutant mice

In order to gain insight into the process of colonization of the bowel by the neural crest-derived precursors of enteric neurons, the development of the enteric nervous system was examined in lethal spotted mutant mice, a strain in which a segment of bowel is congenitally aganglionic. In addition, nerve fibers within the ganglionic and aganglionic zones of the gut of adult mutant mice were investigated with respect to their content of acetylcholinesterase, immunoreactive substance P, vasoactive intestinal polypeptide and serotonin, and their ability to take up [³Hserotonin. In both the fetal gut of developing mutant mice and in the mature bowel of adult animals abnormalities were limited to the terminal 2 mm of colon. The enteric nervous system in the proximal alimentary tract was indistinguishable from that of control animals for all of the parameters examined. In the terminal bowel, the normal plexiform pattern of the innervation and ganglion cell bodies were replaced by a coarse reticulum of nerve fibers that stained for acetylcholineserase and were continuous with extrinsic nerves running between the colon and the pelvic plexus. These coarse nerve bundles contained greatly reduced numbers of fibers that displayed substance P- and vasoactive intestinal polypeptide-like immunoreactivity, but a serotonergic innervation was totally missing from the aganglionic bowel. During development, acetylcholineserase and uptake of [³Hserotonin appeared in neural elements in the foregut of mutant mice on the 12th day of embryonic life (E12), about the same time these markers appeared in the forgut in normal mice. By day E14, neurons expressing one or the other marker were recognizable as far distally as about 2 mm from the anus. The appearance of neurons in segments of gut grown for 2 weeks as expiants in culture was used as an assay for the presence of neuronal progenitor cells in the segments of fetal bowel at the time of explantation. Both acetyl- cholinesterase activity and uptake of [³Hserotonin developed in neuronsin vitro in expiants of proximal bowel between days E10 and E17. At all times, however, the terminal 2mm of mutant but not normal fetal gut gave rise to aneuronal cultures. In some mutant mice rare, small, ectopically-situated pelvic ganglia were found just outside aganglionic segments of fetal colon. Uptake of [³Hserotonin, normally a marker for intrinsic enteric neurites, was found in these ganglia.The experiments suppport the hypothesis that the terminal 2 mm of the gut in lethal spotted mutant mice is intrinsically abnormal and thus cannot be colonized by the precursors of enteric neurons. The defect seems to be specific in that both cells and processes of intrinsic enteric neurons, including all serotonergic and most peptidergic neurites, seem to be excluded from the abnormal region while extrinsic nerve fibers, including sympathetic and sensory axons, are able to enter the aganglionic zones. Since examination of neural progenitor cells has failed to reveal a significant proximo-distal displacement of these cells through the enteric tube during development of the murine bowel, a defect in the migration of precursor cells down the alimentary tract to the terminal gut seems unlikely to be substantially involved in the pathogenesis of aganglionosis. This conclusion is supported by the normal enteric nervous system in proximal regions of the mutant gut and the presence of enteric type neurons outside of, but at the same level as the aganglionic region.